textproduct: Quad Cities

KEY MESSAGES

- Active pattern this week to bring numerous rounds of showers and storms with heavy rain possible.

- There is a Marginal Risk, Level 1 out of 5, for severe storms across the western outlook area Monday evening into the overnight hours. Primary hazards will be heavy rain and damaging winds.

- An elevated flash flood risk may develop mid-week with repeating rounds of storms. Rainfall totals over 2 inches are likely for parts of the area, with localized areas of 4+ inches possible, leading to rises on area creeks and streams.

SHORT TERM /THROUGH MONDAY/

Issued at 230 PM CDT Sun Sep 13 2026

Elevated post-frontal showers and mid/high clouds have held down temperatures this afternoon, currently ranging from the upper 50s across the far north/northwest to mid 70s far southeast. Shower coverage looks to increase along and south of the Highway 34 counties through late afternoon and into the early evening associated with a band of ~850mb fgen. Marginal instability with MUCAPE of several hundred J/kg could support a few isolated storms in this area as well. Once this upper wave shifts to the east early tonight, high pressure will build into the region and skies will gradually clear out. A relatively dry air mass in place and light winds will allow temperatures to fall into the mid to upper 40s north/northeast of the Quad Cities to mid to upper 50s across the south.

The surface high will shift to the east into the Great Lakes region on Monday as low pressure organizes in the Northern Plains. This will result in increasing southeasterly flow across eastern Iowa and northwest Illinois with warmer temperatures anticipated (near 80 F far south to low/mid 70s for much of the remainder of the outlook area). An elevated wing of warm air advection passing through later Monday morning into the afternoon, will likely lead to scattered showers and isolated storms across the area. The highest chances are NW of the Quad Cities (40-60%) with 10-30% elsewhere.

LONG TERM /MONDAY NIGHT THROUGH SUNDAY/

Issued at 230 PM CDT Sun Sep 13 2026

Overnight Monday, a closed heights center positioned over the Northern Rockies negatively tilts as it lifts into south-central Canada. Widespread showers and storms (80-100% coverage) are expected along the cold front moving in from the northwest, but lackluster mid-level lapse rates will put a hamper on the overall instability (750-1500 J/kg of SBCAPE). This is forecasted to, once again, limit the overall severe potential. However, there is a brief window where a mid-level jet boosts the 0-6-km shear along the front to 45+ knots north of I-80. The SPC has maintained a Marginal Risk, Level 1 out of 5, for severe storms across the far western counties, with the primary hazard being damaging winds. By Tuesday, storm coverage and instability decreases as upper- level dynamical support weakens. The cold front is forecast to stall out over northern Missouri, similar to today's set up, keeping storm chances around through the end of the week.

The second half of the week is going to remain stormy. A ridge over the Southeast and a slow-moving shortwave trough over the western CONUS is forecast to pull multiple, weak subtropical troughs northeastward into the Midwest. With the stationary front from Tuesday's system acting as the source of lift, scattered showers and storms will likely develop daily. With saturated grounds expected after the rounds of rain today through Tuesday, the flood threat will become more elevated with each subsequent round, and WPC has highlighted the area with a Slight Risk (level 2 of 4) for excessive rainfall through much of the week.

In terms of rainfall totals, latest LREF probability for 2"+ are 60-80% northwest of the Quad Cities and 20-40% to the southeast. There is uncertainty though in the axis (or axes) of heaviest rainfall with the LREF 10th-90th percentile spread showing a 2-3 inch difference areawide. Therefore, while the probabilities are low (10-20% across the NW outlook area, much lower elsewhere) for 5+ inches of rainfall, the ensemble spread is suggesting that latest model guidance may be undercutting the high-end totals.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 607 PM CDT Sun Sep 13 2026

Rain showers are now southeast of the area, and moving away from all sites at the start of the period. A cool, quiet, VFR night is in store for the area, possibly with some river valley fog over far northwest Illinois, but increasing mid clouds later tonight should keep that from being a widespread problem. By morning, a warm front aloft will begin to sweep northeast over the region, bringing a band of rain showers and possible thunder from soutwest to northeast over the region. These showers are expected to favor a northerly track over northeast Iowa, and I have included a Prob30 for 4SM rain showers at CID and DBQ Monday during the mid morning and afternoon hours, (16-20Z).

Winds will be light tonight, and turn to the east/southeast Monday morning, increasing to 10 to 23kts by mid morning,(15-17z).

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.